Fasting Hypoglycemia on 18F-FDG PET/CT Scan

A 74-year-old woman with a histological diagnosis of lung cancer underwent F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for staging. She complained of headache and palpitations during the exam. Her blood glucose level was low at 2.4 mmol/L. We administered an intravenous glucose injection, and the level rapidly rose to 4.0 mmol/L after which her symptoms improved. In addition to bilateral adrenal FDG uptake (Picture 1, arrowheads), FDG also showed uptake in anterior pituitary gland (Picture 2, arrows). Other exams that were subsequently performed revealed no abnormal findings. She was diagnosed to have lung cancer with a hyperfunction of the adrenal and anterior pituitary glands due to fasting hypoglycemia. PET/CT is an important imaging modality; however, patients aren’t allowed to consume any food prior to the start of the exam. Therefore, the patients sometimes experience hypoglycemia. Following partial pneumonectomy, she has not shown any clinical signs of recurrence or metastasis.